The recent proliferation of devices employing wireless technologies has led to the incorporation of devices with multiple wireless communication systems. Bluetooth is often used to connect and exchange information between mobile phones, computers, digital cameras, wireless headsets, speakers, keyboards, mice or other input peripherals, and similar devices. Bluetooth allows for the creation of a personal area network (PAN) between a master and up to seven slaves. WLAN systems, such as those defined by IEEE 802.11 protocols, are typically directed to longer range communications and larger networks. WLAN communications provide relatively high data rates over relatively long distances, offering an easy interface to existing network infrastructures. Accordingly, it is often desirable to implement both Bluetooth and (WLAN) radios in a single device. Furthermore, it is also often desirable to implement both communication modules on a single integrated circuit (IC), for example in conjunction with other components of the device in a system on a chip (SoC) architecture.
Despite the advantages of providing Bluetooth and WLAN functionalities, careful design is required to minimize interference and improve the quality of service. For example, the physical proximity of the Bluetooth and WLAN modules may result in the transmission of one radio generating interference that impairs reception in the other radio. These problems may be exacerbated when the design of the device involves the sharing of a single antenna among both radios.
In the context of devices employing Bluetooth and WLAN radios, a Bluetooth transmission can be characterized as interference with respect to WLAN reception of the desired signal. WLAN and Bluetooth radio both may operate within the 2.4 GHz industrial, scientific and medical (ISM) band. Although the bandwidth of the Bluetooth signal is fairly narrow at 1 MHz as opposed to the 20 or 40 MHz of a WLAN channel, the Bluetooth protocol utilizes frequency hopping, making it difficult for the WLAN radio to settle on a stable channel and desensitization of the WLAN receiver may result. As such, WLAN reception performance may be degraded if interference due to the Bluetooth transmission is not mitigated.